Manufacture of artifical silk



,May 21, 1935. A. J. 1.. MORlTZ 2,001,742

MANUFACTURE OF ARTIFICIAL SILK Filed April 17, 1954 comm/1150 Y 600575 By A ORNEY Patented May 21, 1935 UNITED STATES MANUFACTURE or aa'rmcar. snx Adrian 1., 1.. man, nun. N. 0., asaignor a American Erika Corporation, Erika,

corporation of Delaware Application All! 11, 1934, Serial No. 121,044

This invention relates to the art oi manufacturing artificial silk, and more particularly to a process of and apparatus for forming freshly spun artificial silk threads and the like into packages, which threads possess desirable qualit.es such as relatively high tensile strength, uniformity in denier, and improved dyeing properties. The invention is applicable to the production of artificial .silk threads and the like when formed in accordance with the viscose process, but with slight modifications this method may be equally well employed in the production of artificial silk threads when formed by any of the known processes such as the cuprammonium process, the acetate process or the nitrocellulose process.

It has been recognized in the past that the ten sile strength and dyeing properties of the finished artificial silk thread may be greatly improved if the thread is placed under tension while it is' still fresh after its passage from the spinning bath Numerous methods have been proposed for accomplishing the giving of uniform tension to succeeding portions of the thread, and of these methods one involves the use of a series of glass rods arranged in the path of the thread between the'spinnerets and a collecting device so that the threads may be interlaced with the rods in such manner as to provide a braking or drag action upon the thread. While the practice of this method did produce certain beneficial results, it has been found that the method is not entirely satisfactory since the braking action with the resultant tension placed upon the thread has been found in most instances to be of an irregular and uneven character.

It has been proposed in this art to lead the thread from the spinning bath to a pair of positively driven cylinders or drums in such manner that the thread contacts with only a small portion of the periphery of each of said drums, and this procedure was carried out for the purpose of obtaining a constant stretch of succeeding portions of the thread as they passed between the drums since'the second drum was operated at a higher peripheral speed than the first one. The thread after being stretched was then passed to the collecting device. In a modified procedure involving the general method just referred to, a collecting or winding member was substituted for the second drum and the peripheral speed of said wind-' ing devices was caused to be operated at a constant higher peripheral speed with respect to that of the first drum so as to effect a stretch between the drum and the winding member.

In still another of the proposed methods for eflecting the tensioning and stretching of the thread, a pair of positively driven drums are employed with .the thread being passed entirely around the circumference of each of the drums. one or more times, whereby when the second drum in the path of travel of the thread is operated at a higher peripheral speed thanthe first, the thread. as it passes between the drums is stretched at a constant rate with respect to sueceeding portions thereof before it is passed to a collecting device for packaging. However, so far V with no uniformity in the size of the thread being obtained while, when substantially no slippage occurs so that a constant stretch is given to the thread, the method fails to compensate for certain mechanical and chemical irregularities inherent in any process of spinning artificial silk produced from cellulosic solutions.

Another recent development involves the use of a plurality of idlingrollers arranged in a group at one place in the path of travel of the thread from its place of formation 'to the collecting device, and the thread is drawn over these rollers by a drawing godet which is contacted by the thread in such a manner that slippage is permitted between this godetand the thread.

Such a process is intended to be used so as to compensate for the mechanical and chemical irregularities inherent in the formation a of the thread. This prior process as defined permits of a control of the drag placed upon the thread by its contact with the idling rollers due to the employment of braking means for the respective idling rollers, and while this process does to some extent compensate for the irregularities above referred to, such irregularities are not entirely compensated for and the present invention is intended as an improvement thereover. D

An object of the present invention is to overcome the difliculties heretofore encountered in the production of artificial silk threads and the like, such as results from the irregularities in the mechanical equipment and chemical failures inherent in the formation of artificial silk threads, and the invention contemplates an apparatus by which the present process can be efiiciently practiced wherein a uniform stretch, or a gradually increased elongation of the thread can be had irrespective of the irregularities in the size and character of the spun filaments.

Other advantages and objects will be apparent from the following detailed description when considered in connection with the accompanying. drawing wherein Fig. 1 is a diagrammatical front view of one form of the invention,- I Fig. 2 is a diagrammatical side view of the structure shown in Fig. 1,

Fig. 8 is a atlcal view of the modified form of apparatus made in accordance with this invention, and

Fig. 4 -is a side view of the structure shown in Fig. 3.

Before referring to the drawing in detail it is well to set forth, more specifically examples of. the problems encountered and the broad method for overcoming the same. It is clear that to produce a body of yarn possessing even dyeing properties, the yarn should have even denier throughout and the stretching of the thread to produce this result should be constant providing contraction is compensated for so that the thread will ultimate- 1.! be of uniform denier. One of the conditions tending to interfere with the obtaining of this result is that a somewhat variable action is had in the setting bath on the freshly extruded or spun cellulosic solution and such variable action or fluctuation in the action of the setting bath causes the thread as it emerges therefrom to be non-uniformly coagulated. As an example, it

is well to consider a short section of thread as it emerges from the spinneret. Should this section of the thread be subjected to excessive coagulation by the fluctuation in the action of the setting bath, this section of the thread would be slightly harder than the average section of the thread and would therefore oppose or resist the stretching action which is to be given to the thread. However, if another section of the thread should be coagulated toa degree slightly less than the average coagulation of the thread as a whole, this section would oppose the stretching with considerably less resistance and therefore if no compensationis made for this irregularity in the coagulation, that portion of the thread which does not resist the stretching will be drawn to a much finer denier than the other portion referred to and may possibly be broken in the further processing of the thread. Additionally, drawing rollers of the type commonly used in thisart for stretching the thread tend to rotate with an eccentric action for the reason that it has been found to be substantially impracticable to exactly center such rollers on a positively driven shaft in a manner so that all portions of the periphery thereof rotate about the axis with the same linear speed as the other portions. Furthermore, such rollers have been found to wearunevenly in a very short period of time so that practically all of the rollers after a short period of operation have eccentrically arranged portions along their peripheries. The employment ofsuch rollers results in the thread which is wound thereabout, being caused to travel at a greater peripheral speed when contacting with the portions of the rollers which are thegreatest distance from the roller axis, than is the thread contacting with the portions of the periphery of the roller which are on a lesser radius from the roller center. It will be seen that the use of such a roller results in an abnormal stretch in the thread and must be compensated passes over another thread guide I4 and it is then conducted to another corrugated roller or godet IS. The thread is caused to encircle the roller IS a plurality of times in order to insure a substantially non-slip engagement therewith. After encircling the roller IS the thread is conducted to a spinning pot 16 or to some other suitable form of collecting device such as a bobbin and the like. The preferred manner in which the thread is passed around the corrugated rollers and over the respective thread guides is readily apparent from a consideration of Fig. 2, but it is to be understood that the thread in passing around the roller I3 is so directed with respect to the periphery of said roller, due to the disposition of the thread guides l2 and I4, that the thread contacts with the roller less than 360 of its circumference and preferably contacts with the roller for approximately 280 of its circumference. In addition to this since the roller l3 has a corrugated surface the thread is contacting only with the raised portions of the surface and thus assured substantial slippage of the thread with respect to the roller l3.

In the form of apparatus illustrated in Figs. 3 and 4, the thread is conducted from the spinning bath in which the spinneret I 0 is immersed, to a corrugated roller l3 over which it is passed without being encircled entirely around the same, and the thread is then conducted to a corrugated roller I 5 about which it is wrapped a suflicient number of times to assure against any substantial slippage. The thread, after it is passed around roller l5 is then conducted to a collecting device I 6. No particular means for driving the positively propelled rollers or godets l3 and I5 and I3 and I5, have been illustrated, but it is to be understood that any suitable means may be .used for this purpose, it being intended that the rollers l5 and I5 be operated at a greater peripheral speed than the rollers I3' and Iii respectively in order that a stretching of the thread may be had between the rollers. However, in certain instances to be hereinafter referred to, it will appear that cone pulleying should be utilized at the respective roller .-'and collecting device whereby changes in the respective rates of operation of the pulleys and the collecting device may be effected for producing an elongation in the thread as it is incorporated into apackage .while, at the same time, compensation is obtained for the chemical and mechanical irregularities which are encountered.

In order to obtain a gradual elongation of the thread as it is incorporated into the package being formed so that contraction of the thread in the package will result in the production of an even denier of the thread throughout the packl3 and at the godet I 3 respectively, there will be an increased stretch of succeeding portions of the thread and. therefore, if the thread is incorporated into the package under a constant tension, a gradual elongation in the thread will be had as it is thus formed into the package.

This result can likewise be obtained by increasing the linear speed of the thread by increasing the peripheral speed of both of the godets in either of the, constructions illustrated, that is if the winding tension is increased at a greater rate so as to compensate for the increase in the linear speed of the thread as it is passed from the godet l5 or the godet l5. Furthermore, the godets mayeach be maintained at a constant but different peripheral speed with the package forming tension being gradually increased, or the peripheral speed of one of the godets may be maintained constant while the speed of the other godet is changed and the desired result will be had so long as a compensation is effected by which the contraction permitted by the packaging or winding tension is such that the gradual elongation of the thread is had as it is incorporated into the package.

Aside from the question of compensating for contraction of the thread in the package, the compensation for chemical and mechanical irregularities in the formation of the thread and the processing thereof before it is packaged is an important feature of this invention and as has already been stated the compensation for mechanical and chemical irregularities in the production of the thread may be had by permitting a slippage of the thread with respect to the withdrawal godet I3 or I3 and, although the godets I5 and I5 may be driven at a variable speed with respect to the godets I3 and I 3*, it is preferred that the godets I5 and I5 be driven at a greater but constant speed with respect to the godets first contacted by the thread. It is intended that substantially no slippage occur between the thread and the godets I5 and I5".

In carrying out the process in the manner above set forth if a small section of the thread is coagulated in excess of the average so that it has an increased resistance to stretching, this stiffer section of thread will be caused to be wound tighter .around the first roller I3 or i3, that is it will adhere more closely thereto and consequently the slip age will be temporarily diminished or eliminated and the stretch will be increased so as to thus compensate for the irregularity. If, however, a section of the yarn is coagulated to a degree inferior to the average coagulation of the thread then the friction on the roller I3 or I3 will decrease and an increased slippage occurs so that the lesser coagulated section will not be stretched to an undesired extent.

The same general action in the operation as above referred to will be had when eccentric portions on the peripheries of the rollers I5 and I5 are encountered since the eccentric action of the drawing roller already referred to tends to cause the thread to be pulled at a higher speed at certain points. The variations in the pull on the thread are compensated for by the slippage of the thread on the first roller whether the eccentricity exists in either or, both of the rollers. When a greater pull is given to the thread, the thread being slidably engaged with the periphery of the first roller, travels at a higher speed than the periphery of the roller and thereby relaxes the tension on the section of thread between the rollers; Thus while the slippage on the first roller overcomes the variations in the freshly spun thread as it leaves the spinning bath, and the normal eccentric action of both rollers, the second roller, rotating at a higher peripheral speed than the first roller, causes the thread to be stretched between the rollers and the second roller which may be either I 5 or I5 imparts a constant and substantial uniform tension to the thread before it is taken up by the collecting device.

Whereas, the term packages has been employed throughout the description, it is to be understood that either bobbins or centrifugal pots may be used as the collecting devices, as the form of collecting device employed is immaterial in applying the novel features of the present invention.

No claim is made in this application broadly to compensating for dyeing differences as hereinbefore described. The broad subject matter which includes correcting dyeing differences in packages of artificial silk by increasing the tension on the filaments during the spinning period is claimed in my co-pending application, Serial Number 572,670, filed November 2, 1931, and a divisional application thereof, Serial Number 3,863, filed January 28, 1935.

I claim:

1. The method of producing artificial silk thread and the like of substantially uniform denier, and having improved dyeing properties by gradually increasing the elongation of the thread as it is formed into a package which comprises the steps of extruding the same through a coagulating bath and stretching the thread in its path of travel between the point of extrusion and a collecting device by contacting the thread with a driven godet wheel in such a manner that slippage is permitted thereon, causing the thread to contact with a second godet wheel rotating at a higher peripheral speed, said contact being sufficient to prevent slippage, and changing the speeds of propulsion of the godet wheels during the spinning period whereby a gradual increase in stretch of the thread is obtained while said slippage compensates for tension variations occurring within and during the path of travel of the said thread.

2. The method of producing artificial silk thread and the like of substantially uniform denier, and having improved dyeing properties by gradually increasing the elongation of the thread as it is formed into a package which comprises the steps of extruding the same through a coagulating bath and stretching the thread in its path of I travel between the point of extrusion and a collecting device by passing the thread around a driven godet wheel less than 360* to allow slippage thereon, causing the thread to contact with a second godet wheel rotating at a higher peripheral speed, said contact being greater than 360 to prevent slippage, and increasing the difference in speeds of propulsion of the godet wheels during the spinning period whereby a gradual increase in stretch of the thread is obtained while said slippage compensates for tension variations occurring within and during the path of travel of the said thread.

3. The method of producing artificial silk thread and the like "of substantially uniform denier, and having improved dyeing properties by gradually increasing the elongation of the thread as it is formed into a package which comprises the steps of extruding the same through a coagulating bath and stretching the thread in itsv path of travel between the point of extrusion and a collecting device by contacting the thread with a driven godet wheel, causing the thread to contact with a second godet wheel rotating at a higher peripheral speed, the contact of the thread with one of the godet wheels being sufficient to prevent slippage and the thread contacting with the other godet wheel in such manner that slippage is permitted thereon, and changing the speeds of propulsion of the godet wheels during the spinning period .whereby a gradual increase in stretch of the thread is obtained while said slippage compensates for'tension variations occurring within and during the path of travel of the said thread. ADRIAN J. L. MORITZ. 

